I'm an epidemiologist with an interest in lifestyle and environmental exposures that play a role in the development of chronic diseases. I'm particularly interested in perceptions of risk and how these square with what the science tells us. My book "Hyping Health Risks" deals with these issues. I'm in the Department of Epidemiology and Population Health at the Albert Einstein College of Medicine in New York City and am a Contributing Editor at STATS (Statistical Assessment Service) at George Mason University.

Should Mammography Be Abolished?

It’s important to recognize the limitations and downsides of mammography. But we should be wary of throwing the baby out with the bathwater.

Mammography for the early detection of breast cancer has long been recommended by such organizations as the American Cancer SocietyAmerican Cancer Society, the United States Preventive Services Task Force, the American College of Obstetricians and Gynecologists, the American Medical Association, and the National Cancer Institute. Roughly 37 million mammograms are performed each year in the United States.

For decades there have been pointed controversies over the age at which screening should be initiated and the frequency (every year, every two years). And the more fundamental question pertains to the objective benefits of mammography – that is, how many lives are actually saved due to detecting potentially fatal breast cancers at an earlier stage.

In spite of these controversies, the value of mammography screening has been an article of faith in the medical community, among American women, and among breast cancer advocates.

English: Woman undergoing a mammogram of the right breast (Photo credit: Wikipedia)

However, in recent years, in addition to the long-standing questions about the actual benefits, the harm caused by screening has been receiving increasing attention. The harm stems from the fact that as many as 30% of mammogram results may be “false positives.” First, biopsies are performed on suspicious-looking entities on the X-ray that turn out to be benign, and, second, some women undergo treatment (surgery, radiation, and chemotherapy) for cancers that are indolent and would never have threatened their life. This is referred to as “over-treatment.”

As a result of new studies showing smaller benefits than had been claimed in the past and, especially, the new attention to the adverse effects of mammography, the use of mammography is being questioned in a radically new way.

The authors, Nikola Biller-Adorno, a medical ethicist, and Peter Jűni, a clinical epidemiologist, were part of an expert panel convened by the Swiss Academy of Medical Sciences to review the evidence regarding mammography screening.

They make three main points:

• First, clinical trials of mammography screening date from an earlier period. In the past 25 years breast cancer treatment has improved dramatically, even for women with advanced disease, and the death rate from breast cancer has been reduced by 27 percent between 1990 and 2005.

The authors ask: “Could the modest benefit of mammography screening in terms of breast-cancer mortality that was shown in trials initiated between 1963 and 1991 still be detected in a trial conducted today?”

• Second, they emphasize the emerging evidence that the harms of mammography outweigh the benefits. A recent publication based on extended follow-up of the Cancer National Breast Screening Study indicates that 22 percent (106 out of 484) of screen-detected cancers were over-diagnosed. “This means that 106 of the 44,925 healthy women in the screening group were diagnosed with and treated for breast cancer unnecessarily, which resulted in needless surgical interventions, radiotherapy, chemotherapy, or some combination of these therapies.”

On the question of whether there is a benefit from mammography, a Cochrane review of 10 trials involving more than 600,000 women showed no evidence that mammography screening reduced overall mortality.

• Finally, the authors point to the wide gulf separating women’s perceptions of the benefits of mammography and objective assessments of its actual effects.

In a survey of women’s perceptions about mammography, 72 percent of women said they believed that mammography reduced the chances of dying of breast cancer by at least half, and 72 percent also thought that at least 80 deaths would be prevented per 1,000 women screened.

In reality, objective assessment of the data indicates a reduction of 20 percent in breast cancer mortality and 1 breast cancer death prevented.

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